According to the World Health Organization, 7.6 million people worldwide died from cancer in 2008. It is well known that cancer is a generic term relating to a large group of diseases that can affect any part of the body. One defining feature of cancer is the rapid creation of abnormal cells that grow beyond their usual boundaries, and which can then invade adjoining parts of the body and spread to other organs in a process referred to as metastasis.
Metastasis is the main cause of mortality in cancer and depends on two key processes: cell migration of cancer cells invading into adjacent tissues followed by intravasation into blood/lymphatic vessels and tumor vasculature, which give access to the blood-stream (1). Cancer metastasis is known as a complex, multi-step process that leads to the spread of cancer throughout the body and sometimes requires a therapeutic approach that differs from the approach that was chosen for treating the primary cancer.
For example, in colorectal carcinoma, one of the most common cancers, approximately 50% of colorectal carcinoma patients develop liver metastases at some point during the course of their disease (2). Patients who are candidates for surgical resection of their liver metastases can expect a prolonged survival or even a cure. Unfortunately, only 10% to 25% of patients are candidates for liver resection and in patients with unresectable metastases, chemotherapy is the treatment of choice.
Complete response to a treatment in cancer is usually defined as the disappearance of target lesions on imaging. However, as reported by Benoist, S. et al. (2), in more than 25% of cases, macroscopic residual disease was found during surgical exploration at the site of liver metastases that were considered to have disappeared based on imaging. In addition, in patients with no obvious disease at surgery, microscopic cancer was observed in the resected specimen from the site of initial liver metastases in 80% of patients. Finally, in patients with no more tumor observed and in whom the site of complete response was left in place, in situ recurrence was observed in 74% of cases after 1 year.
These data show that although complete response seen on imaging may be a useful criterion for evaluating the efficacy of chemotherapy, it does not mean the cure of cancer in most cases. In addition, while certain types of metastatic cancer are treated as a chronic disease, thereby prolonging the lives of the patients, many types of metastatic cancer are still considered incurable.
A peptide termed “T101” that is encoded by a cDNA unique for the human thymus was identified. This peptide was implicated, inter alia, for the treatment of cancer via its role as a stimulator of the immune system (WO 2006/046239, 3). WO 2006/046239 demonstrates that T101 is able to stimulate the immune system and to reduce tumor size, suggesting that the peptide affects the proliferation of cancer cells. Treatment of cancer by using T101 was also suggested in WO 2007/122622 (4), which demonstrates, inter alia, the effect of T101 on the development of various types of tumors. The peptide T101 was also described in WO 2007/091240 (5), relating to treatment of immunological diseases and WO 2008/075349 (6), relating to treating or preventing a disease involving a cell having T1/ST2 receptor.